Arcellx has revealed encouraging interim data from its Phase I study of CART-ddBCMA in patients with relapsed or refractory multiple myeloma.
The company plans to present new data with a median follow-up of 26.5 months at the 65th American Society of Hematology (ASH) Annual Meeting and Exposition taking place 9-12 December 2023 in San Diego, California, US.
Arcellx entered a global strategic collaboration with Kite Pharma in December 2022 to co-develop and co-commercialise CART-ddBCMA for the treatment of this patient group.
Just 38 patients were evaluable for efficacy and safety analysis in June 2023 based on a median follow-up of 22 months following treatment. All patients have poor prognostic factors with 38 of 38 (100%) patients triple-refractory, 26 of 38 (68%) penta-refractory, and 34 of 38 (89%) refractory to last-line of treatment by International Myeloma Working Group (IMWG) criteria.
At baseline, 24 of 38 (63%) had at least one high risk clinical feature, defined as presence of EMD, BMPC >60% or B2M >5.5. All 38 patients had at least three prior lines of therapy.
The interim CART-ddBCMA Phase I clinical results demonstrate deep and durable responses. There was a 100% overall response rate (ORR) achieved in all patients per IMWG criteria. Twenty-nine of 38 evaluable patients achieved a complete response (CR) or a stringent complete response (sCR) and 35 patients achieved a very good partial response or higher.
The Kaplan-Meier method estimated PFS rates for six, 12, and 18 months were 92%, 74%, and 67% respectively. Durable responses were also observed in patients with high-risk features (EMD, BMPC ≥60%, or B2M ≥5.5 mg/L at baseline) and high-risk cytogenetics.